3 Green Roofs Over One Million Square Feet

At PowerHouse Growers, we believe that one of the premier tools, if not the premier tool, for researching green roofs and green walls is the International Greenroof & Greenwall Projects Database hosted by Greenroofs.com. Containing information on over 1,500 projects, the total area covered in this database is in excess of 32 million square feet. To put that size into perspective, imagine 555 football fields floating atop your nearest city skyline.

The idea behind this initiative is to create the world’s first comprehensive list of all green roof and green wall projects completed internationally. Linda Velazquez, the publisher of Greenroofs.com, was actually the first to issue an international call for a Greenroof Projects Database back in 2005 when she presented at The World Green Roof Congress in Basel, Switzerland.

She recognized that the green roof industry was “well-established, documented, and supported.” However, there was a “lack of a cohesive resource” tying all of that information together. Noting the importance of equipping all stakeholders with this valuable information, the database has since served as the “one central location” that offers “free access” to researchers and other interested parties. Being searchable by a variety of options including size, slope, location, and building type, the database also allows users the capability to conduct research readily and with ease.

The GreenRoofs.com database search parameters..

Curiosity piqued, I decided to use the database to find out what green roofs were the biggest in the world. It turns out that there are some pretty big green roofs. There were only three in the database though that met a particular threshold – green roofs over one million square feet.

Using the “greater than” search function, I discovered these three green roofs over one million square feet:

3. ACROS Fukuoka Prefectural International Hall (1,049,406 sq. ft.)

ACROS, which stands for “Asian Crossroads Over the Sea,” is a green roof that was built in 1994 in Fukuoka, a city on the northern shore of southern Japan. The roof’s 15 stepped terraces, each equivalent to 1 story, overlook the river that leads to Hakata Bay and stands atop a building that contains over 1 million square feet of multipurpose space.

The designer, Emilio Ambasz, an Argentine-born, American architect relied upon his “Green Over the Grey” philosophy to guide him in replacing all of the land displaced by the construction of the building with vegetation. Due to limited space, Japan is often challenged with balancing its need to expand physical structures with its need to retain green space. The ACROS Fukuoka Prefectural International Hall accomplishes both and its award-winning design has provided the residents of Fukouka with a number of benefits, most notably the opportunity to rest and exercise in nature where “nature” seems to severely lack.

Emilio Ambasz has been quoted saying, “I see my task as an architect as that of reconciling our man-made Nature with the organic one we have been given.” Certainly, Mr. Ambasz accomplished this with creating the world’s third largest green roof.

Millennium Park in Chicago is one of the world’s largest green roofs. Image via GreenRoofs.com

2. Millennium Park (1,067,220 sq. ft.)

Millenium Park in Chicago sits right on the edge of Monroe Harbor on the shoreline of Lake Michigan. An industrial wasteland before, this site now attracts over four million people every year turning it into Chicago’s second largest tourist attraction. The 24.5-acre park, funded by a public-private partnership between the City of Chicago and a number of private sources, is home to a number of venues including the , the , and the McCormick Tribune Ice Rink.

The park, now celebrating its 10th year anniversary, is definitely one of the most well-known green roofs in the world; however, it’s also been one of the most controversial, mainly due to the higher than expected cost of $490 million. Not to worry though, according to a recent study, Millennium Park “generates an estimated annual revenue of $1.4 billion in direct visitor spending and an additional $78 million in tax revenue.”

1. Financial District Banco de Santander (1,075,000 sq. ft.)

In the Boadella del Monte suburb of Madrid, Spain, the world’s biggest green roof sits atop the Financial District Banco de Santander. Spanning more than 100,000 square meters, this green roof is a combination of extensive and intensive green roof systems that were built between 2003 and 2005.

Unfortunately, not much information is available on this green roof. And being the largest listed in the database, I was hoping for a bit more. Nevertheless, I received the answer I was looking for – three of the world’s largest green roofs over one million square feet each.